Topics

1

General Questions and Answers / How to export the data of surfacebandstructure?

« on: June 4, 2019, 15:14 »

Dear Quantumwise staffs:
   In ATK2019.03, surfacebandstructure can be calculated, but the data in the hdf5 file can't be export as 'txt' file？ and it can only polt the A(ε,K║)?
 what about the 2D Brillouin District at the definite Z along the C axis? just like the paper you post on the NANOLETTER(DOI:10.1021/acs.nanolett.7b02511). could you help me for these problems?

2

General Questions and Answers / A problem of finite bias in spin calculation

« on: May 8, 2019, 08:56 »

Dear QuantumwiseStaffs:
       Recently, I am tring to reappear this work :doi.org/10.1088/1361-648X/ab1732.  few days ago, I faced the converge problem:https://forum.quantumatk.com/index.php?topic=6045.0
      Thanks to Mr Anders Blom, his advice is useful , I get the converged result in 0V bias. But  when bias applied, the convergence is geting worse. Even small bias voltage such as  0.1V or -0.1V applied, the calculation still get converged.
     I have tested many LCAO Basis SET, and found that HGH basis set is suitable for the bulk and device configuration at 0V voltage.   And I found that  if i use GGA -PBE for nonspin calculation, all bias voltages will well converged. Is it means that my device configuration is  reasonable？
    My  ATK version is 2019.03  and the author's  is Atk2015, does the different atk version cause these problem?
    In  nonspin calculation, only spin up electron(default) is consided, and in spin calculation with SGGA, spin up and down electron are consided. can we  only consider  spin up(down)  electron?  does these two types of Hamilton in density matrix cause the numberical error  in the NEGF  step?
   I will upload my py files , could you tell me the reason of the poor convergence?  If you want to reappear the work, what bias set you will use?
   PS; all the converge skills in the guidelines i have tried,  only Mr Anders Blom's advice is work in this calculation.

3

General Questions and Answers / A license error

« on: April 19, 2019, 07:32 »

Dear  Quantumwise staffs:
     There are something wrong with my license files or lmgrd. The calculation was stopped suddenly last night, we checked the log file and find that 'License Error: Unable to obtain a required license for the
requested license feature. It could mean there are no valid
licenses left, a problem with the connection to the license
server, or the license file does not contain the requested feature.
See below for more details'
     we restart the lmgrd and sloved the problem , and restart our calculation, but it dead again after five or six hours. the log file is the same as before.
    we want to know, what is wrong with the license and lmgrd and how to slove it .
     

4

General Questions and Answers / what's the difference between the two models in version 2018.06

« on: March 4, 2019, 03:45 »

Dear  Quantumwise staffs:
  I  have calculated two MTJ  models, the only difference is the electrode extend region length.and I get two converged results.The log file and the hdf5 file show that these two results  are almost the same. and in the log file , I found the central region SCF process are different. In the end I calculated the Electrostaticdifferencepotential,and the difference is almost zero .
  But the size of hdf5 files are different. The elctest4.hdf5 is 154MB,and the elctest5.hdf5 is 220MB.
can you tell me if the configuration in elctest5.py  suitable? because this configuration is helpful for convergence.
I guess  the central region in both models are calculated in the same way. Is that so?   and why the two hdf5 files have different size?

5

General Questions and Answers / Can we use ATK to calculate the real-space PDOS?

« on: February 25, 2019, 10:46 »

Dear all,
 I want to calculate the real space resolved DOS using ATK. As shown in the attached picture, the LDOS maps of a bulk system are sampled in different heights over the atomic plan. In ATK script generator, I find that the the PDOS can be  projected to different projections, but no xyz projection is found (I have tested spin.x, spin.y and spin.z. It is not the x, y and z coordinates).  It seems that PDOS of a bulk system can not be  resolved in real-space as the open device system. Besides, the Bloch State can be calculated in specific k-point and quantum number. And it is exactly a class inherit from the GridValues object(As described in https://docs.quantumatk.com/manual/Types/GridValues/GridValues.html#gridvalues-c), thus it is convenient to analyse Bloch State in real-space. In a way, Bloch State can represent the intensity of DOS. The problem is that I want to analyse the system in a large range of Energy from -2 eV to 2 eV (with 0.01 eV step), and  the Bloch State calculation can not be assigned to specific energy level.
Can you give me some advices?
Thanks,

6

General Questions and Answers / The spin magnetic tunnel junction cant get converged

« on: February 21, 2019, 14:24 »

Dear  Quantumwise staffs:
  I  calculated  a magnetic tunnel junction  with exchange correlation SGGA-PBE ,but  I cant get  converged.  the best  result  is  dE and dH can reduce to  10-3.
I  have  tried all  methods  in  the convergence  guide but failed ,   and  all  pseudo potential  are tested  ,but it  does not work , could  you  please  help me ?  thank  you 
  my log file is over 400k  I cant post it